These houses basically - and readilly (with installed solar systems including Photovoltaic and Solar Hot Water, achieve a "Net Zero" energy requirement: In the span of one year on average, and all within their property envelope (urban settings too) they produce an amount of energy equal to, or more than ("Net Positive"), the energy they consume. That also requires choosing energy efficent appliances (fridges can be power hogs otherwise) that consume low Killowat hours of energy. LED lights are excellent. induction cookers as well. The key thing on Passivhaus design is that the house has a very high R-value all round (walls can be a foot thick of insulation and roofs are R 80) and the house must be air-sealed to a specific blower door pressure test stardard.
Passivhauses do not have to look like bunkers or lunar outposts by necessity. The Mill Creek Net Zero home in Alberta is one pleasing example, or this example in Salem, Oregon. Because the houses are so well sealed (in contrast to regular built houses that leak air badly), air exchangers are a necessity and key to having fresh air. One of the benefits of a passivhaus is that the air is extremely fresh. To save conserve space heating energy heat recovery ventillators are used. Some heat recovery ventillators can be anywhere from 95 to 99% efficient. In some cases - even in cold climates, the passivhaus standard built house actually doesn't need an auxilliary heating system, but the City officials can get a little freaked out and demand one anyway. Germany has many of these houses. Passivhauses can also work in hot climates as well.